Neil Patrick Harris has heartwarming reason why he doesn’t want to know which twin is biologically his

Neil Patrick Harris has shared the heartwarming reason why he doesn't want to know which of his twins are biologically his.

Harris, 51 and husband David Burtka, 49 are parents to two children - twins Gideon and Harper - who are 13 years old.

Harris said he doesn't want to know which of the twins are biologically his (Instagram/@nph)

Harris and Burtka first met in 2004 and after building a solid friendship, they went public with their relationship in 2007.

They later welcomed their twins in 2010 before getting married in Italy in 2014.

The twins were conceived via surrogate, which involved two embryos from an egg donor - meaning the pair are non-identical as two separate eggs were used.

Speaking to American broadcaster and journalist Barbara Walters in 2014, Harris explained: "We inserted one of my sperm and one of David's sperm into two eggs with the hope that they would both take, just because we both wanted to be dads biologically. Both took, miraculously."

Harris also explained that he has no interest in finding out which of his twins are his biologically.

He explained: "I have no interest in [finding out]. We are their parents and I love them implicitly."

While the couple have no idea about who the biological father is for each of their children, Harris said that they have suspicions based on behaviour.

However, the How I Met Your Mother star did not reveal what those suspicions were.

Harris recently offered a glimpse into family life, explaining that his daughter, Harper, is 'unfazed' by horror films, but did end up staying in his bed for four nights after watching The Shining.

Speaking on The Tonight Show Starring Jimmy Fallon, Harris said: “What do you say to a girl who wants to watch horror movies?

“Do you say ‘Absolutely not’ because then she wants to watch them more?

“She just kept asking and persisting, and so we watched The Shining last week.

“I don’t know if it was a good call."

Speaking about her reaction to the movie, he added: “I said, ‘So what did you think?’ And she said, ‘I’m mildly disappointed.'

“She has slept in our bed for, like, the last four nights.”

The pair welcomed the twins via surrogate (Instagram/@nph)

The dad-of-two recently shared an adorable photo of his family on Instagram, while celebrating Father's Day.

In tribute to husband David, he said: "David, you’re the most amazing father I know. Thanks for your dedication and commitment to parenting our children. They are made better because of you. Happy Father’s Day!"

Alongside the heartfelt words was a photo of David with the twins and their dogs.